Unless you are building a round or organically shaped house made from cob or adobe (in which case, cool!), keeping the corners of your floor, walls and roof square is a critical task that lasts for the entire construction process. Constant re-evaluation of your squareness will make your life easier at each subsequent step of the building process.

Or so we’ve heard.

There are many good reasons to “square as you go,”and I think we can all agree it’s a best practice for building anything, but there are many forces working against square corners, including:

Lumber is seldom straight,

Fasteners (nails and screws) seldom go in level,

Weight or pressure can shift boards,

Existential chaos and entropy

Of course, understanding you need square floor joists is a completely different animal from having square floor joists. Here’s where I reiterate that Alan and I are far from experts and can only share our unique trial-and-error experiences. When we began our procrastiprepping, we agreed we’d need to check for squareness frequently. What we didn’t realize at the time was, this checking and rechecking would also require fixing and refixing: if something is out of square, you have to do something to correct it, something that may interrupt your building timeline. It can be incredibly frustrating, repetitive and disheartening, but also necessary. I don’t want to be on the roof six months from now, realizing I have to cut a weird miter to fit my non-square upper left corner 12 feet in the air. I mean, we’ll probably have to do that anyway, but at least if I make efforts now, I won’t be blaming my past self, just my present/future self. Talk about existential chaos.

Anyway, there are a number of references and established processes for checking the squareness of your floors and walls while building. As a hobby painter (one who has built her own canvases), I like the “measure your diagonals to see if they match” method:

And my high school friends thought we’d never need geometric theorem notation! Ha!

What this means is, if the length of both diagonals match, the square or rectangle has 90-degree, or square, corners. If one diagonal is shorter than the other, then the corners with the shorter length have an “obtuse” angle, or an angle wider than 90 degrees.

Another way of telling whether you are in or out of square is the Pythagorean Theorem:

This method is helpful when you can’t access all corners of your square or rectangle, like tall walls, or if you are working alone. The shorthand version (demonstrated at the bottom of my most excellent drawing), the 3-4-5 rule allows you to just measure off three feet on one side, mark it, four feet on the other side of the angle, mark it, then measure the diagonal between the two marks. If the diagonal is equal to five feet, you’ve got your 90-degree, square corner. The 3-4-5 rule works because Math.

Once you’ve determined you’re not square, which is most of the time, there are several ways to fix it, most of which involve propping, pushing, pulling or yanking. John Carroll’s book, “Working Alone: Tips and Techniques for Solo Building” and the This Old House website are good resources for time-tested methods. But our Fencl floor proved a special challenge, and not in the good-special way, because the wheel hubs got in the way and prevented us from squaring the whole floor at once. Plus, the steel rods that hold the house to the trailer frame also held everything pretty firmly in place, so we didn’t have much control.

Here’s the problem we faced with the floor’s left-hand corner, closest to the trailer tongue. You can see that the corner is about a quarter-inch out of square in comparison to our speed square. Oh Noes!

Incidentally, I heart speed squares. They’re invaluable. We have this big orange one and a smaller steel one. When we get to the roof rafters, we’ll probably get a big framing square too, the one that look like the letter L and has all the rafter dimensions printed on it.

Our problem was compounded by the fact that one of the steel rods held runs through the sill just a foot or two away from this corner. Therefore, we couldn’t just push the far corners closer together, because the rod was holding the outside of the sill in place. The wrong place, but in place all the same.

We adapted one of the classic squaring techniques (attaching a diagonal chain and tightening it to pull opposite corners closer together) to a smaller area. We attached the chain to the sill in two places with several nails, then attached a turnbuckle to the chain. You can see the welded steel rod under Alan’s right arm in the third photo.

Sorry for the changing POVs in these photos… it’s making me a bit motion sick.

Another aside: The guy at Lowes didn’t know what a turnbuckle (the hooked thing in the middle photo) was when we asked, so it took us 20 minutes longer to find them than necessary. If you need to know where to find turnbuckles in Lowes and probably Home Depot, they’re with the door and gate hinges, instead of the rope and chain.

By tightening the turnbuckle, we accomplished the bending of nails most efficiently. But we also managed to bring this corner into square, so the sacrifice of six nails was glorious indeed.

Success! Mostly! At least it’s noticeably better than it was! Beer for all!

Ok, so it’s not perfect, but it’s within our arbitrary tolerance of “less than 1/8th of an inch.” It’s also not perfect because we accept that, although the corner is close to square, the sill will bulge out around the steel rod a bit, meaning the wall won’t be perfectly straight, but I think we can work with that problem better than kerflunky corners. At least, I hope we can.

Your Turn!

What rules, such as “always check for square corners,” have you given yourself?